NBLs with 2 x 250s

I intend to run my NBLs active, they are currently passive - I just need to source another olive 250 of the same vintage to go active. However, that means I’m currently running passive with 1 NAP 250. The other NAP 250 is switched off.

It seems I can technically run 1 channel of one 250 for left speaker and 1 channel of the other 250 for the right speaker. It would be done by plugging into two separate 4 pin outputs of the Hicap. It seems I should get the benefit of the 250 power supplies dedicated to each speaker.

I know its not a recommended route and is a temporary measure until I source another 250. My question is:

  1. Will it damage the 250s only having 1 channel driven? - the unused channel will still get the signal, but no speaker cable will be connected to it.
  2. Do I need to source some NAP 135 4pin to XLR cables to stop the signal going into the 250 for the unused channel?

Thanks in advance


This should work, and I can’t see how any damage should occur. Just use the supplied DIN-XLRs. If you’re worried though then do run it past Naim.

Thanks Richard,
That’s reassuring, I’ll give it a whirl tomorrow

That made a huge difference! I spent all of yesterday making my way through Curtis Mayfield and Grace Jones back catalogues, with a bit of 808 state. It’s so much more punchy and dynamic.
I remember seeing somewhere that 1 X 250 was the minimum for NBLs, but off the back of this I’d say that 1x 250 results in a fairly compromised system with NBLs. I can see why 135s are so revered , and also ups the ante on sourcing another 250 for active!

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Using two stereo amps in the ‘pseudo-monoblock’ configuration are almost always better than using a single stereo amp, driving both channels (the exception is when the amps are not tonally similar). As you have seen, you are getting closer to a pair of NAP135s. I actually have compared 2x250 (mono) with 2x135, and the latter are definitely even better-for a variety of reasons. But I would say that the 250s so driven are closer to 135s than they are to their conventional stereo configuration.
Not suprisingly, using a pair of single-channel only NAP500s is also very much better sounding then running both channels of the 500.

The 2x 250s in mono, took a little of the shine off when I got my 3rd 250 for active with a snaxo. It is better, but just not to the same degree as I’d imagined. I’m in Australia, and 135s are pretty rare in these parts. The next change is probably selling all the 250s , hicap and snaxo, and going with a 300 dr.

By far, I preferred active 250’s into my NBL’s over a 300, albeit non-DR’d.
Think very carefully before selling the 3 x 250’s for a single 300.

That’s interesting @Blythe, so maybe upgrade the 82 to a 52, or an xps on the nd5xs ?
I have a hipcap dr on the olive snaxo and two olive hipcaps on the 82. Supercaps are also few and far between. What are you running?

I believe at the time that I went from passive to active, I was running a CDX2/XPS2, 252/Supercap, 250, NBL’s.
Adding the SNAXO/Supercap/ +2 more 250’s was an eye opener.
I actually had a blind, home-test comparing a 300 Vs the active 250’s.
Not knowing if I was listening to active 250’s or a passive 300, my dealer did an A/B comparison.
Within seconds of me hearing A/B I knew I preferred B even though A was clearly better than my passive 250.
B turned out to be the active 250 setup.
It’s so good, I’ve barely changed anything since, apart from I upgraded to CDS3 and more recently turned to streaming. (Plus I’ve always had my LP12 for vinyl).
My 250’s and Supercap are all Olive.

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